The borough measures 9.5 km from west to east and 6 km from north to south. Its highest point is the Brocken, at 1,141 metres above NN, and its lowest is at 215 metres.

The town lies on the German-Dutch holiday road known as the Orange Route.

The Northern Harz Boundary Fault crosses the borough along which runs the watershed between the Weser and Elbe rivers. To the north precipitation flows into the Weser, to the southeast, later northeast, waters flow into the Elbe. This fault line runs through the suburb of Hasserode to the west south west of the city centre and forms the town's castle hill to the south east of the city centre.

Wernigerode is located in the Central European transition subzone of the temperate climatic zone.[5] Its average annual temperature is 9.5 °C; its average annual precipitation is 500 millimetres.

The warmest months are June to August with average temperatures of 16.0 to 18.3 °C and the coldest are December to February at 1.1 to 2.1 °C.

The most rain falls in July, on average 54 millimetres, the least in February, with 30 millimetres on average.

The climate, more precisely the amounts of precipitation and temperatures, are influenced by the orographic rainfall caused by the Harz Mountains. Because the town lies in the rain shadow (leeward side) of the Harz, less precipitation falls here than in similar temperate regions without the protection of a mountain range. In addition the occasional föhn winds that occur result in an increase in temperatures.

There are no written sources confirming exactly when the town was established. According to the latest research – for example, by Eduard Jacobs and Walther Grosse – there were no early relations with the Abbey at Corvey (Weser) and the abbot there, Warin, instead the town name suggests it was a protected clearance settlement.

The first area to be settle was the Klint, where there was a lowland castle, the so-called Schnakenburg. In 1805 the ruins of this castle site were demolished. The only part remaining is Haus Gadenstedt at Oberpfarrkirchhof 12 which dates to the year 1582. At the time of the first settlelement there was still ancient forest, typical of the Harz, on the heights of the Klint, which had first to be cleared, hence the suffix -rode in the town name which means "clearing".

The town was first mentioned in the records in 1121 in connexion with Count Adalbert of Haimar who had moved here from the region near Hildesheim and henceforth was titled the Count of Wernigerode. On 17 April 1229 the settlement was granted town rights along the lines of that for Goslar. In 2004 Wernigerode celebrated the 775th anniversary of that occasion.

As a result of the immigration of new townsfolk from the surrounding villages a new settlement, later called Neustadt, grew up on the northeastern edge of the old town. It was a farming settlement that lay outside the walls of the old town. St. John's Church was built as the parish church of Wernigerode's Neustadt in the last third of the 13th century in the Romanesque style.

Wernigerode contains several interesting Gothic buildings, including a fine town hall with a timber facade from 1498. Some of the quaint old houses which have escaped the numerous fires through the years are elaborately adorned with wood-carving.[3] The Gerhart-HauptmannGymnasium,[8] occupying a modern Gothic building, is the successor to an ancient grammar school in existence until 1825. Brandy, Hasseröder lager, cigars and dyes are among the products manufactured in Wernigerode. The castle (Schloß Wernigerode) of the princes of Stolberg-Wernigerode rises above the town.[3] The original was built in the 12th century but the present castle was built between 1862 and 1893 by Karl Frühling and includes parts of the medieval building.

Wernigerode hosts the Brocken Marathon each October. Wernigerode also has had an American Football club, The Mountain Tigers, since 1993. During the last 19 years this team has played in Germany's Oberliga 4 and Regionaliga 3. Since its inception, it has been a mainstay for American football in the Harz region.